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ASAT target was working research satellite.

It is not just that the Air Force satellite deliberately destroyed by an Air Force missile on Sept. 13 was still transmitting at the time. That much was a requirement in the test of the U.S. antisatellite (ASAT) system, says a Pentagon spokesperson, "so that we could verify impact." What has outraged some scientists is that the chosen satellite was instrumented for studies of the sun, and had been operating until the instant of its destruction as what one solar physicist calls "the backbone of coronal research through the last seven years."

Known as P78-1, the satellite had been launched on Feb. 24, 1979, carrying seven scientific instruments. Only two were in use at the time of the ASAT test, due, the Pentagon says, to "continuing battery degadation." But one of them was a "white-light coronagraph" that had been photographing the sun's outer atmosphere on the way to what scientists hoped would be the first record, made from outside-earth's own atmosphere, of the corona's behavior over a full, 11-year cycle of solar activity. (A coronagraph aboard NASA's Solar Maximum Mission satellite had become useless when "Solar Max" blew three fuses 10 months after its 1980 launching, and was not restored to duty until space shuttle astronauts repaired the satellite last year [SN:4/14/84,p.228].)

"I can't believe that they couldn't find a piece of space junk, really,instead of a working laboratory," says David Rust of the Johns Hopkins University Applied Physics Laboratory (APL) in Laurel Md. "This was a working observatory, so I'm just a little taken aback [by] the SDI [Strategic Defense Initiative, sometimes dubbed 'Star Wars'] people. ... They particularly made a pitch to the university community, to the scientists, in saying this is a 'Manhattan Project' sort of thing, and it's good science and so forth--and then they turn around and blow up a laboratory."

Rust, a supervisor of the APL solar physics program, was also coordinator of satellite observations during the 1980-81 Solar Maximum Year. P78-1 "played a major role in that," he says, and its researchers "have made major strides in explaining how coronal changes affect interplanetary space. They found the first evidence of a comet falling into the sun [SN: 10/17/81,p.244], and you could expect that they'd continue to show some good results, particularly with the solar cycle changing the characteristics of the corona...." As for aPL, he says, our chief reaction here, among severl of us who have used the data, was really one of shock."

The ASAT test was originally to have been aimed at an instrumented, balloon-like vehicle launched into space just for that purpose. But according to the Sept. 2 AVIATON WEEK & SPACE TECHNOLOGY, problems with the target caused delays until "the decision was finally made to use an older, no longer functional satellite already in space...." P78-1 had a "planned, on-orbit lifetime" of only one year when it was launched, and a "maximum design lifetime" of three. And, said one Pentagon spokesperson after the test, it had "outlived it useful life and fit the requirements of the test."

But "useful life" and "design lifetime" are not always synonymous. Design lifetime is a technical specification, used for such purposes as determining the reliability requirements for microcircuits and other components (those tested to higher reliability standards cost more), or scheduling subsequent satellites. Researchers working with scientific satellites and interplanetary spacecraft, however, often plan for the possibility of longer period of operation.

The Voyager 2 spacecraft, for example, exceeded its official design lifetime when it passed Saturn in August 1981, yet even before its 1977 launching scientists of encounters with Uranus in 1986 (Voyager 2 will get there in January) and Neptune in 1989. Similarly, the Viking 1 landing craft, which reached the surface of Mars on July 20, 1976, collected data about the planet for more than six years, yet its formal "spec" had called for only 90 days. "Design lifetime," says an engineer who has worked on some of NASA's interplanetary missions, "is not what I'd fall back on if I were trying to rationalize turning off a working spacecraft."

Even so, the Pentagon spokesperson says that, "based on cost and return-on-investment, P78-1 would have been turned off in early 1987, when ground systems are scheduled to be upgraded." For the ASAT test, he says, "the Air Force made a conscious decision ... [which] considered the loss of the continuing useful scientific data being provided by the two operating experiments."

"If you want to say that I called it a travesty,'" Rust told SCIENCE NEWS, "why you can say that. I think that's perfectly correct characterization."
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Title Annotation:some scientists outraged that functional lab was destroyed by antisatellite weapon
Author:Eberhart, Jonathan
Publication:Science News
Date:Sep 28, 1985
Words:773
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